Exercise device

ABSTRACT

The present invention provides a system and method of exercise utilizing fluid containing bladders. The bladders may be in communication with each other so that compression of one bladder causes the fluid to be transferred to a neighboring bladder. The system may be used to exercise complementary muscle groups. Additionally, the system may be adjustable to provide different workout levels or so that the device can be used to exercise a variety of muscle groups.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.11/692,270 filed Mar. 28, 2007, now U.S. Pat. No. 8,425,385, entitledRESISTANCE THERAPY, which is a continuation of U.S. application Ser. No.11/101,942 filed Apr. 8, 2005, now U.S. Pat. No. 7,207,930, entitledEXERCISE DEVICE, each of which are herein incorporated by reference intheir entirety.

FIELD

The invention relates to an exercise system and method utilizingexpandable bladders to provide resistive forces to the muscles beingexercised.

BACKGROUND

Exercise has long been known to be beneficial for people of all ages. Inthe past, many people were able to exercise simply by carrying outroutine daily tasks that previously were labor intensive. The modernage, however, has succeeded in eliminating many “inconveniences” of lifethat involved physical exertion, and consequently there has been anincreasing need for people to find other ways to exercise in order toachieve better health.

Today, a wide variety of exercise equipment is available for helpingpeople achieve better health. Some devices and equipment help peopleachieve a cardiovascular workout, while other devices and equipmentallow people to focus on muscle toning, strengthening, and development.Devices and equipment designed for muscle strength and developmenttypically involve a muscle or muscle group applying a force inopposition to a resisting mechanical force generated by the exercisedevice. Thus, current devices and equipment can be highly specializedfor the development of a particular muscle or muscle group.

While the ability to focus on a particular muscle or muscle group isbeneficial, this specialization often neglects to allow for developmentof complementary muscle groups. Complimentary muscle groups includemuscles that allow a person to move a part of their body and then returnit to an original position. One example of complimentary muscle groupsare biceps and triceps, which allow a person to bend their arm and thenextend it again. Typically, exercise equipment that specializes indeveloping bicep muscles are not targeted for developing triceps withouteither modification of the equipment, repositioning of the exerciser, orboth. Free weights useful for developing biceps, for example, may be tooheavy for tricep development and would require an exerciser to choosewhich muscle group to develop during any set of exercises. As a resultof this specialization, often people need to use multiple devices orcomplex exercise systems in order to strengthen or develop thesecomplementary muscle groups.

Some exercise equipment requires a relatively uniform amount of exertionthroughout the entire range of motion. Free weights, for example,provide the same weight resistance regardless of how far they have beenlifted. Other exercise machines provide for variable resistance over therange of motion in which they are used. For example, some exercisemachines simulating bench presses of weights may use camming mechanismsto vary the mechanical advantage given by the machine to the exerciseras the bar or grip is moved by the exerciser's arm extension. Thus, asan exerciser exerts a force to move the bar or grip, the machine can bedesigned to become progressively more difficult or more easy to move.Likewise, the use of a spring in an exercise device can result inrequiring progressively increasing forces in order to further compressthe device.

While such devices have been effective in some ways, they also sufferfrom disadvantages. Such machines tend to be large, being of high weightand requiring a large amount of space. These machines may also bedifficult to use, requiring not only weight adjustment, but alsoadjusting the position of the user.

Another problem with such devices, or the use of conventional weights,is one of safety and convenience. If an exerciser lifts free weightsconnected to a bar, for example, relaxation of the muscles exercisedduring lifting may cause the weights to fall and injure the exerciser.Thus, it is difficult for a person exercising by such methods to safelystop in the middle of an exercise stroke, as the weights must bereturned to a resting position.

SUMMARY

The present invention provides a system and method of exercise utilizingexpandable bladders. One or more of the bladders may define a reservoirthat holds a fluid that can be at least partially transferred from onechamber or bladder to another. Alternatively, one or more of theexpandable bladders may have compressible fluid or gasses inside that,when compressed, provide resistance to exercise the user's muscles.

One potential benefit of the devices of the present invention is thatthey may be small in size. In addition, some embodiments of theinvention do not require heavy weights in order to achieve adequateresistance for muscle development. These features of the presentinvention may be implemented in a manner that also allows the devices tobe easily transported or conveniently stored when not in use.Alternatively, the entire device, or just the patient contactingportion, can be made as a single-use disposable device. This minimizes,if not eliminates, the risk of disease transmission. Regardless ofwhether disposable or reusable, the size of devices according to thepresent invention allows use in a confined space, like an airplane, orother locations where the use of traditional exercise equipment wouldnot be feasible.

Additionally, it is believed that several embodiments of the presentinvention also are safer to operate than some current exerciseequipment. In this regard, the present invention can be used forlow-impact work outs. Such work outs are particularly useful fordisabled individuals, such as a stroke patient, partially bed riddenpatients, or patients recovering (or as part of a post-operative therapyprogram) from surgery. Another application of the present invention isto build bone mass, for example, to delay the progression ofosteoporosis.

One embodiment of the present invention involves a series of fluidlyconnected expandable bladders to provide resistive forces to the musclesbeing exercised. Two or more bladders may be connected, for instance byapertures or tubes that allow air or other fluid to be transferredtherethrough. In this embodiment, the system includes a first bladderhaving a first stiffness and a second bladder having a second stiffness,wherein the second stiffness is greater than the first stiffness.

As a result, it is possible to achieve different levels of resistancefrom the exercise device in this embodiment depending upon which portionis being utilized or compressed. In particular, a first force is neededto compress the first bladder in order to force air or other fluid intothe second bladder, while a second, different force is needed tocompress the second bladder in order to force air or other fluid intothe first bladder. The bladders may be configured or oriented so thatcompression of a first bladder helps a user develop a first musclegroup, while compression of the second bladder helps develop a secondmuscle group. Preferably the second muscle group is complementary to thefirst group.

Upon removal of the compressive force, the expanded bladder compressesor returns toward its original shape by forcing some of the fluid backto the other bladder until reaching an equilibrium condition. The tubeor aperture providing fluid communication between two or more expandablebladders also may be configured to partially restrict flow from onebladder to another. This may extend the time needed for the bladders toreturn to an equilibrium state. Restriction of flow between two or morebladders can be achieved, for instance, simply by providing a smallaperture that allows for a more gradual transfer of fluid or gas fromone bladder to another.

Alternatively, the aperture or tube may be formed from elastic materialso that flow therethrough is substantially or fully restricted until thepressure gradient exceeds a desired level. In this configuration, aperson using the device would need to impart a first force in order todisplace some or all of the fluid or gas in a bladder, and then wouldneed to impart a second, potentially smaller force in order to maintainequilibrium of the compressed device. As the force applied is reduced,pressure in the expanded bladder may cause the aperture to expand oropen to allow the air or fluid to return to the previously compressedbladder.

In yet another alternative embodiment, the bladders need not be in fluidcommunication with each other. Instead, the bladders may be capable ofsurrounding a compressible gas, such as air, so that resistance by eachbladder is achieved either by the compression of the gas, the resilientexpansion of the bladder material, or both.

The bladder system can be incorporated into an exercise device ormachine to work any muscle group, including, arm, leg, chest, back,shoulder, abdominal, or neck muscles. As mentioned above, and discussedmore fully below, the system also may be useful in allowingcomplimentary muscle groups to be exercised.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 depicts a bladder exercise system of the present invention;

FIG. 2 depicts the bladder exercise system of FIG. 1 with an additionalrestrictive band disposed around a bladder;

FIG. 3 depicts the bladder exercise system of FIG. 1 acted upon by acompressive force;

FIG. 4 depicts the bladder exercise system of FIG. 1 including a controlvalve:

FIG. 5 depicts the bladder exercise system or FIG. 1 including a fillvalve;

FIG. 6 illustrates an alternative embodiment where one or more bladdersmay be selective removed from the exercise system;

FIG. 7 depicts a bladder exercise system of the present inventionincluding multiple serially linked bladders;

FIG. 8 depicts a bladder exercise system of the present inventionincluding multiple linked bladders;

FIG. 9 depicts an exercise system including multiple bladder exercisesystems;

FIG. 10 depicting an bladder exercise system including accordionbladders;

FIG. 11 depicts an alternative bladder exercise system of the presentinvention;

FIG. 12 depicts the accordion bladder system of FIG. 11 in a firstposition;

FIG. 13 depicts the accordion bladder system of FIG. 11 in a secondposition;

FIG. 14 is a schematic representation of exercising opposing muscles ona limb;

FIGS. 15A-B are schematic representations of a first embodiment forexercising agonist and antagonist muscles of opposite limbs;

FIGS. 16A-B are schematic representations of a second embodiment forexercising agonist and antagonist muscles of opposite limbs;

FIGS. 17A-B are schematic representations of exercising the same muscleson opposite limbs;

FIG. 18 depicts a cuff bladder exercise system of the present invention;

FIG. 19 depicts a sectional view of the cuff bladder exercise system ofFIG. 18;

FIG. 20 depicts the cuff bladder exercise system of FIG. 19 in useduring a bicep exercise;

FIG. 21 depicts the cuff bladder exercise system of FIG. 19 in useduring an abdominal exercise;

FIG. 22 depicts an adjustable cuff bladder exercise system of thepresent invention;

FIG. 23 depicts the cuff bladder exercise system of FIG. 19 includingmultiple serial bladders; and

FIG. 24 depicts the cuff bladder exercise system of FIG. 19 includingmultiple stacked bladders.

DETAILED DESCRIPTION

The present invention provides a system and method of exercise utilizingexpandable bladders. The bladder system can be a stand-alone exercisedevice or alternatively may be incorporated into another device ormachine to work muscles for arms, legs, chest, back, shoulder, abdomen,or the neck.

Referring now to the drawing figures, FIG. 1 illustrates one embodimentof a bladder system 10 of the present invention that uses a plurality offluidly connected bladders to provide resistive forces to the musclesbeing exercised. The bladder system 10 includes first and secondbladders 12 and 14 in fluid communication with each other, such asthrough a tube 16. Alternatively, portions of the expandable bladdersmay be disposed adjacent to each other to define one or more aperturesthrough which a fluid may travel. Unless indicated otherwise herein, theterm “fluid” may include air or other gases in addition to liquids.

Returning once again to the embodiment of FIG. 1, a compressible ornon-compressible fluid 18 is disposed within the bladders 12 and 14,such that a compression of one of the bladders 12 or 14 forces the fluid18 through the tube 16 into the opposite bladder 12 or 14. It is alsocontemplated by the present invention that a malleable foam, gelatin, orother similar material can be placed in either or both of bladders 12and 14. Such a material could occupy all or part of the volume of thebladder(s) and could be used either with or without the fluid.

The size, shape, construction, physical or material properties, andcomposition of the expandable bladders may be varied according to adesired use or performance of the exercise device. For example, whilethe bladders 12 and 14 shown in FIG. 1 are substantially similar in sizeand shape, one bladder may be configured to be substantially larger thanthe other. For instance, one bladder may have a volume of about 1.5times or greater the volume of the other bladder under similarconditions of fluid pressure. Alternatively, the difference in volume ofone bladder may be about 2 times or greater than the volume of anotherbladder, or may even differ by more than 4 times the volume of theother.

Providing a difference in bladder volumes is one way to achieve adifferent level of resistance that can be created when exerting pressureon the device during exercise. For instance, it is believed that theamount of exertion required to compress the smaller bladder, or todisplace fluid from the smaller bladder into the larger one, will beless than the amount of exertion that may be required to compress thelarger bladder a similar amount, or to displace a similar amount offluid from the larger bladder into the smaller one.

Without being bound to any particular theory, it is believed that thereason for this difference in required exertion to displace similaramounts of fluid is that the relative increase in volumes required toaccommodate the increase in fluid will be different. In other words, thesmaller bladder will need to expand more than the larger bladder for agiven amount of additional fluid, and therefore it will provide greaterresistance to expansion. Thus, the resulting difference in resistancethat can be achieved may be tailored to provide different workout levelsfrom the same device. This feature may be beneficial when one musclegroup is capable of exerting greater force than a complimentary musclegroup.

Likewise, the shapes of the bladders may be designed to providedifferent amounts of resistance to a given increase of fluid orpressure. For example, while the shapes of the bladders shown in FIG. 1are generally rounded or perhaps spherical, it is also possible that oneor more of the bladders may be oblong in shape. As the pressure or fluidlevel increases, the mid-section of the oblong shape initially mayexpand more readily. The bladders may have other shapes as well, such asa pancake shape, an accordion shape, a belt or tubular shape, or thelike.

The construction of the bladders also may be varied to provide differentlevels of resistance. For instance, the wall thickness of one bladdermay be greater than the wall thickness of another bladder. In oneembodiment, the wall thickness of one bladder is about 1.25 times orgreater than the wall thickness of a second bladder. Greater differencesin wall thickness may be used to provide even greater differences inresistance. For example, in one embodiment the wall thickness of onebladder may be about 2 times or greater, or even about 3 times orgreater, than the wall thickness of a second bladder. U.S. Pat. No.5,033,457, the contents of which are expressly incorporated by referenceherein, also discloses other manners in which bladders can be providedto have different resistances or flexibilities.

Once the potential value of utilizing different bladder wall thicknessesfor the present invention is understood from the discussion above,skilled artisans would appreciate that there can be several ways thatthese different wall thicknesses can be achieved. For instance, abladder may be formed of multiple layers, or plies, of material. Thus,in an embodiment where one bladder wall thickness is about 2 times orgreater than another bladder wall thickness, the first bladder may beformed by forming an additional layer of material over a first layer.The use of multi-ply constructions also allows the material and/orphysical properties of one ply or layer to differ from the properties ofanother layer.

In another embodiment, the walls of the bladders may be constructed toinclude reinforcing fibers. The material used to form the reinforcingfibers may have a different modulus of elasticity (E) than that of thematerial used to form the bladders. The difference in modulus ofelasticity may be used to provide even greater differences in resistancebetween the bladders. For example, in one embodiment the wall of onebladder include fibers having a modulus of elasticity of about 2 timesor greater, or even about 3 times or greater, than the modulus ofelasticity of a second bladder.

In another alternative embodiment, a second layer of material formedaround a bladder need not fully cover the first layer. As shown in FIG.2, for example, a second layer may form a restrictive band 18 aroundonly a portion or region of a bladder 12. The restrictive band 18 may bedesigned to be removable and interchangeable with one or more otherrestrictive bands having varying degrees of resistance. Additionally,the bands may be configured to fit over more than one expandablebladder. In this manner, a user of the device may further customize thedegree of resistance of one or more expandable bladders by selectingfrom a plurality of bands.

The physical properties of the materials used to form an exercise deviceof the present invention also may be selected to provide a desired levelof resistance. For example, the modulus of elasticity E of material usedto form one bladder may be about 1.25 times greater or more than themodulus of elasticity of material used to form another bladder. Onceagain, the difference in modulus of elasticity may be even morepronounced, such as by 1.5 times or more, or by 2 times or more,depending on the degree of different resistance that is desired.

Likewise, the elasticity of one expandable bladder may be greater thanthe elasticity of another expandable bladder to provide differentresistance. For example, the elasticity of material used to form a firstbladder wall may be about 1.5 times or greater than the elasticity of amaterial used to form a second bladder wall. In other embodiments, thisdifference may be about 3 times greater, or even about 5 times greater.

It is believed that many different materials may be used to make devicesof the present invention. By way of illustration, components of thepresent invention may be formed from urethanes, natural or syntheticrubbers, or the like. Preferably, the materials used to form theexpandable bladders are elastomeric material that can stretch or expandand then substantially return to its original shape once pressure isreleased.

Additionally, the components of the present invention may be formed froma biodegradable material. It is contemplated that the present inventionmay be provided as a disposable exercise device. As a disposable device,the present invention could have a limited useful life, after which thedevice is easily disposed and reclaimed.

It should be understood that any selection of potential variationsdescribed above may be used either in combination with other variationsor on its own. Thus, it is not necessary that any embodiment of thisinvention utilizes every variation to create a difference in resistance.In fact, many of the design elements described above may be“neutralized” from creating a noticeable difference in resistancebetween two expandable bladders. This can be achieved by making thedesign factor substantially the same for one bladder as another (e.g.,bladder wall thickness, shape, and size may be relatively the same whileother design elements are varied). In addition, in some instances it maybe desirable for the design and performance of one bladder to besubstantially the same as another expandable bladder.

Another way to express the differences in resistive forces that mayresult from design variations between expandable bladders is bystiffness or by effective spring constant of each bladder. For example,regardless of how the variations are achieved, it is preferred that oneexpandable bladder has an effective spring constant k₁ that is differentfrom the effective spring constant k₂ of a second expandable bladder.Hooke's Law defines a spring constant k as the ratio of an appliedstatic force to the linear displacement of a spring. Regardless of howthe differences are characterized (e.g., resistance level, stiffness,effective spring constant, etc.), it is preferred that the differencesare at least about 10 percent or greater, and more preferably thebladder designs result in a difference of about 25 percent or more. Insome cases, a more pronounced difference may be desired, such asdiffering by about 50 percent or more, or even by about 100 percent ormore (i.e., one bladder requires twice as much force to be exerted on itin order to achieve the same effect).

FIG. 3 illustrates the effect of exerting a compressive force F₁ on thefirst bladder 12 of one embodiment of the invention. The compressiveforce F₁ causes the fluid from the first bladder 12 to travel throughtube 16 and into the second bladder 14. In response to the additionalfluid, the second bladder 14 may expand to accommodate the additionalvolume. Alternatively, the fluid in the first and second bladders may becompressible gas, such as air or nitrogen. Thus, some embodiments of theinvention may utilize a compressible fluid and one or more relativelynon-expandable bladders so that exertion of a compressive force F₁ mayreduce the internal volume of one or more bladders.

Returning to the embodiment shown in FIG. 3, upon removal of thecompressive force F₁, the second bladder 14 contracts and eventually mayreturn to approximate its initial shape and size. The higher pressureexerted by either the expanded wall of the second bladder, thecompressed of gas inside the bladder, or both, results in thecontraction of the second bladder 14 and expansion of the first bladder12. In turn, this causes fluid from the second bladder 14 to travel intothe first bladder 12 as the device returns to an equilibrium position.

The bladder system 10 of the present invention provides a resistanceprofile R to the compressive force F1. Initially, to force fluid fromthe first bladder 12 into the second bladder 14 the compressive force F1exerted by a user must be equal to or greater than a threshold force TF.The threshold force TF is the force required to initiate expansion ofthe second bladder 14. This relationship is more likely to be observedwhere the fluid is liquid or relatively incompressible, but may be lesslikely observed if the fluid itself can be compressed. In cases wherecompressible fluid is present, the fluid may initially compress untilreaching a level of pressure that meets or exceeds the threshold forceof the second bladder. In general, the threshold force TF may bedependent on the elasticity or effective spring constant k of the secondbladder 14. Thus, a low elasticity or high effective spring constant k₂will likely result in a higher threshold force TF, while a highelasticity or low stiffness k₂ is likely to result in a lower thresholdforce TF needed before the second bladder expands.

Upon exceeding the threshold force TF, the second bladder 14 will beginto expand, still providing a resistance against the compressive forceF₁. The resistance profile R can be a uniform resistance, where thestiffness k₂ and/or size of the second bladder 14 are selected toprovide a relatively uniform resistance. Alternatively, the stiffness k₂and/or size of the second bladder 14 may be selected to provide anincreasing or decreasing resistance profile R.

Additionally, the tube 16 or aperture between two bladders may also beconfigured to resist the compressive force F1. For example, the diameterof the tube 18 can be selected to restrict the rate at which fluid canbe transferred from one bladder to another. Whereas a relatively largediameter tube 16 may impart only negligible restriction on fluid flow, asmall cross-sectional area and longer length connection between twobladders may significantly increases pressure losses during transfer offluid from one location to another.

One feature that can be obtained by utilizing a connection that at leastpartially restricts fluid flow is that sudden relaxation of muscles bythe exerciser need not result in the device suddenly and immediatelyreturning to its original shape. Instead, there may be a more gradualreturn to equilibrium. For instance, in one embodiment, restricted fluidflow that results from full removal of compressive force may result inthe delaying the return to initial shape of the device by about 0.25seconds or more. In other embodiments, the restriction in fluid flowresults in an even greater delay, such as about 0.5 seconds or more,about 1 second or more, or even about 5 seconds or more. These delayscan be used to help ensure safe operation of the device. In addition theability to control the rate at which fluid flows through the tube 16 oraperture also may be beneficial in customizing the resistance that auser will experience from the device during a workout.

The viscosity of the fluid 18 also may be used to control the resistanceof the exercise device. The fluid viscosity is selected to provide aspecific maximum flow rate through the tube 16. A more viscous fluidwill have a decreased flow rate, providing a greater resistance. A lessviscous fluid will have an increased flow rate, providing a decreasedresistance. The benefits that may be obtained from selecting viscosityof the fluid to achieve a desired maximum flow rate are similar to thebenefits described above for restricting fluid flow by choosing anappropriate cross-sectional area for the aperture or tube 16 connectingtwo bladders.

Referring to FIG. 4, the fluid connection between two bladders may beconfigured so that the connection has a variable cross-section throughwhich fluid may flow. That is, the size of opening between two bladdersmay be changed to control the rate at which fluid flows between them. Asillustrated in FIG. 4, one way the cross-section may be varied is byoperation of a valve 20 or similar device capable of selectivelychanging the size of the opening between the two devices. The valve 20may be manually controlled or adjusted or alternatively may beoperatively connected to an automated control system. In addition, thefluid connection 16 between bladders may be expandable. Thus, theconnection may initially be small, or perhaps even substantially closed,but can expand in response to an increased pressure differential fromone side of the connection to the other.

Thus, the bladder system 10 may include a control valve for regulatingthe diameter of tube 16 or flow of the fluid. In a fully open position,the tube 16 has a maximum diameter allowing for a maximum flow rate ofthe fluid 18. In a closed position, the control valve 20 minimizes thediameter of the tube 16, resulting in a minimum flow rate of the fluidthrough the tube 16. In one embodiment, the valve may be fully closed tosubstantially restrict or prevent any fluid flow. An exemplary controlvalve 20 includes a housing positioned about the tube 16. A threadedmember may then be screwed into a threaded orifice in the housing.Rotation of the threaded member gradually causes the cross section ofthe tube 16 to be restricted or decreased. A knob may be provided on thethreaded member to allow for easier manual adjustment.

Referring to FIG. 5, one or more bladders may include a mechanism forcontrolling or adjusting the fluid pressure in the bladder system 10. Inthe illustrated embodiment, the control mechanism may be one or morefill valves 22. Skilled artisans would appreciate that a great varietyof fill valves may be used, some non-limiting examples of which includescrew caps, interference fit plugs (such as, for example, may be foundon beach balls, or the like), or needle valves (such as found onsporting equipment), and the like.

A pressure gauge, transducer, or other similar means may be used inconjunction with the fill valve 22 to determine the fluid pressure inthe bladder system 10. To increase the resistance to the compressiveforce F₁, fluid is added, through the fill valve 22, into the bladdersystem 10. The fluid may be pumped or injected into the bladder system10 from a pressurized container, being added until the desired fluidpressure is present in the bladder system 10. To decrease the resistanceto the compressive force F1, fluid may be evacuated from the bladdersystem 10.

The fill valve 22 may be opened, allowing some or substantially all ofthe pressurized fluid to exit the bladder system 10. Providing a fillvalve not only allows fluid to be added or removed from the bladdersystem 10 in order to increase or decrease fluid pressure in a bladder,but also the valve may be useful in allowing for a substantial amount ofthe fluid to be removed in order to more conveniently store or transportthe exercise device.

In an alternative embodiment, one or more of the bladders of theexercise device 10 may be removed from the fluid connection to anotherbladder. As shown in FIG. 6, one or more bladders may be selectivelyconnected to or removed from the fluid connection 16. This configurationnot only allows for adjustment of fluid levels and convenient storageand transport of the exercise device, but also allows different bladdershaving different properties to be used interchangeable on the device. Inone embodiment, the exercise device comprises a plurality ofinterchangeable bladders where the resistance of at least one bladderdiffers from another bladder by about 10 percent or more, and morepreferably differs in resistance by about 20 percent or more. Aninterchangeable bladder may be secured to a fluid connector 16 withclamps, by interference fit, or in any other suitable manner.

Preferably, the exercise device 10 has sufficient structural integrityto permit a wide range of initial fluid pressure (i.e., the internalpressure of the system without application of a compressive force F₁)without experiencing significant pressure loss over time. For purposesof this application, significant pressure loss is defined as the devicelosing more than 25 percent of its pressure over a 24-hour period ofnon-use. In some embodiments, it may be desirable for the device to becapable of withstanding an initial fluid pressure of at least about 50psi without significant pressure loss, and more preferably can hold atleast about 100 psi. It should be understood, however, that the devicemay be subjected to significantly greater pressures when subjected tocompressive forces.

In the above examples, the exercise system 10 has been depicted ashaving a pair of bladders 12 and 14. However, it is contemplated thebladder system 10 can include multiple fluidly connected bladders. Forexample, the exercise system 10 may have 3 or more bladders, or even 5or more bladders. Providing a combination of bladders may be beneficial,for instance, when the range of body motion involved in the exercise islong. For instance, stomach, arm, or leg exercises may involve bodymotion over a sufficiently large area to warrant use of more than justtwo bladders. In addition, providing more bladders may allow for greatervariation of resistance over the range of motion.

A non-limiting example of the use of 3 or more bladders in an exercisedevice 10 is illustrated in FIG. 7. As shown, the bladder system 10 mayinclude multiple bladders serially connected. As generally shown in FIG.7, a first bladder 30 may be fluidly connected, via first tube 32, to asecond bladder 34. Second bladder 34 may then be fluidly connected, viasecond tube 36, to a third bladder 38. Optionally, the third bladder 38also may be fluidly connected to a fourth bladder 38 via third tube 40.As a compressive force F₁ is applied to the first bladder 30, the fluidis compressed into the second, third, and fourth bladders 34, 38, and42, providing a resistance to the compressive force F₁.

The stiffness of the second, third, and fourth bladders 34, 38, and 42may be selected to provide a prescribed resistance profile R to thecompressive force. For example, each the second, third, and fourthbladders 34, 38, and 42 can have the same stiffness k. Alternatively,each of the second, third, and fourth bladders 34, 38, and 42 can havedifferent stiffnesses. The different stiffnesses are selected andarranged to provide the resistance profile R.

Likewise, flow rates between the bladders also may be varied to achievea desired resistance profile R. The bladders 30, 34, 38, and 42 areserially connected with tubes 32, 36, and 40. As described above, thetubes 32, 36, and 40 provide a specific flow rate therethrough and canbe used to adjust resistance the compressive force F₁. The tubediameters are selected to provide a prescribed resistance profile R tothe compressive force F₁ and may be adjustable in the manner describedabove. A larger tube diameter will have an increased flow rate,providing a lesser resistance. A decreased tube diameter while provide adecreased flow rate, providing an increased resistance. Each of thetubes 32, 36, and 40 can have the same tube diameter, providing auniform flow rated through each of the tubes. Alternatively each of thetubes 32, 36, and 40 can have different tube diameters, wherein the tubediameters are selected and arranged to provide the resistance profile R.

As discussed above, the sizes and arrangement of the bladders 30, 34,38, and 42 can be selected to provide a prescribed resistance profile Rto the compressive force F₁. Referring to FIG. 7B, the bladders 34, 38,and 42 are arranged in a decreasing size arrangement. Alternatively, asshown in FIG. 7C, the bladders 34, 38, and 42 are arranged in anincreasing size arrangement.

The above-described elements may be used individually or in combinationto design a bladder system 10 to provide a specific resistance profileR.

It is not necessary for every bladder of the exercise system 10 to belinked or connected serially with the others. Referring to FIG. 8, theexercise system 10 may include a central bladder 12 with multiplesecondary bladders attached thereto. Each of the secondary bladders maybe fluidly connected to the central bladder 50 with tubes or aperturesin the manner already described above. In some embodiments, only aportion of the secondary bladders may be in fluid communication with thecentral bladder. Thus, some secondary bladders may be self contained inorder to provide some cushioning or stabilization for the user. As acompressive force F₁ is applied to the central bladder 12, the fluid iscompressed into fluidly connected secondary bladders providing aresistance to the compressive force F1.

As discussed above, each of the bladders in any embodiment may be sizedor otherwise designed to have a desired stiffness in order to provide aspecific resistance profile R in response to a compressive force F₁.Likewise any other design parameter discussed above also may be usedwith the embodiments illustrated in FIGS. 7 and 8.

In the above examples, the exercise systems 10 have been described asbeing a single collection of bladders. However, it is contemplated thatmultiple bladder systems 10 can be used in combination to provide aselected resistance profile R to the compressive force F₁. Referring toFIG. 9, a pair of bladder systems 70 and 72 are used in combination toprovide a effective resistance profile R for the overall combination.Each of the bladders systems 70 and 72 can have the same or differentindividual R₁ and R₂ resistance profiles. The individual resistanceprofiles R₁ and R₂ are selected to provide the effective resistanceprofile R of the combined systems 70 and 72.

Other bladder configurations also may be used with the presentinvention. For instance, one or more of the bladders may be formed froman inelastic (non-elastomeric) material so that it does not expandsignificantly when subjected to increased pressure during normaloperation of the device. This type of bladder may be useful withcompressible fluid or may also be used as an overflow reservoir. Inaddition, one or more bladders may have a pleated or accordionconstruction as illustrated in FIG. 10.

Referring to FIG. 11, the bladder system 100 also may include a ventport 104, such that when a compressive force is applied to the bladder102 air is evacuated from the bladder 102 through the vent port 104.Upon removal of the compressive force, the bladder 102 reverts to itsoriginal form, drawing air in through the vent port 104.

Bladder 102 provides a resistance to the compressive force, wherein theresistance is dependent on the material properties of the bladder 102.The higher stiffness k of the bladder 102 results in the higherresistive force. The lower stiffness k of the bladder 102 results in thelower resistive force.

The vent port 104 may also be utilized to provide resistance to thecompressive force F1. The diameter of the vent port 104 is selected toprovide a specific flow rate of the fluid 108 from the bladder 102through the vent port 104. A larger vent port 104 diameter will have anincreased flow rate, providing a lesser resistance. A smaller tubediameter vent port 104 will have a decreased flow rate providing anincreased resistance.

The bladder system 102 of the present invention provides a resistanceprofile R to the compressive force F1. Initially, to force the fluidfrom the bladder 102 through the vent port 104 the compressive force F1must be equal to or greater than a threshold force TF. The thresholdforce TF is the force required to initiate expansion of the bladder 102.The threshold force TF is dependent on the stiffness k of the bladder102, and the characteristic of the vent port 104. Upon removal of thecompressive force, the bladder expands drawing air into the bladder 102through the vent port 104.

The bladder system 102 may include a control valve 106 for regulatingthe diameter of vent port 104 and/or the flow rate of the fluid. In afully open position, the vent port 104 has a maximum diameter allowingfor a maximum flow rate of the fluid, providing a minimum resistance. Ina closed position, the control valve 106 minimizes the diameter of thevent port 104, resulting in a minimum flow rate of the fluid through thevent port 104, providing a maximum resistance. Exemplary control valvesare discussed above with respect to FIGS. 4 and 5.

Referring to FIGS. 12 and 13, the bladder 108 is an accordion bladder,providing first and second resistances. When a compressive force F_(C)is applied to the accordion bladder 108, air is evacuated from thebladder 108 through the vent port 110, providing the first resistance.When an expansive force F_(E) is applied to the accordion bladder 108,air is drawn into the bladder 108 through the vent port 110, providingthe second resistance. Both the first and second resistances aredependent upon the stiffness of the bladder 108 and the configuration onthe vent port 110.

The first and second resistances can be used to exercise opposingmuscle. Referring to FIG. 14, a schematic of a leg extension/hamstringexercise machine is shown. When a leg L is moved into an extendedposition, the quadriceps leg muscles are contracted. Similarly, when theleg L is moved into a flexed position, the hamstring muscles arecontracted. The accordion bladder 108 of the present invention can bepositioned in a leg machine, such that the bladder 108 provides aresistance to both flexion and extension of the leg. For example, thebladder 108 is positioned in the leg machine such that when the leg isflexed, a compressive force F_(C) is applied to the bladder (see alsoFIG. 12). The bladder 108 provides a first resistance, resisting thecompressive force F_(C). When the leg is extended, an expansive forceF_(E) is applied to the bladder 108 (see also FIG. 13). The bladder 108provides a second resistance, resisting the expansive force F_(E). Thefirst and second resistances exercise the hamstring and quadricepsmuscles. It is contemplated that the bladder can be used as a standalone device or incorporated into an exercise machine systematicallyexercising opposing muscles groups, such as, chest/upper back,abdominal/lower back, quadriceps/hamstring, biceps/triceps, etc.

Referring to FIG. 15A, the bladder system 10 of the present inventioncan be positioned in a leg machine, such that the bladders 12 and 14provide forces to agonist and antagonist muscles of opposite legs. Anagonist muscle is a muscle that contracts when another muscle relaxesand an antagonist muscle is a muscle that relaxes when another musclecontracts. For example, when performing a leg extension exercise, thequadriceps muscle (the agonist muscle) contracts and the hamstring (theantagonist muscle) relaxes when the leg is extended.

In an exemplary embodiment, the bladder 12 is positioned in the legmachine such that when a first leg L₁ is extended from an initialposition, a first force F₁ is applied to the bladder 12. The bladder 12provides a first resistance R₁ to the quadricep muscle (agonist muscle)resisting the extension of the first leg L₁. Simultaneously and inresponse to the first force F₁, the fluid from bladder 12 is forcedthrough the tube 16 into bladder 14, expanding bladder 14. The expansionof bladder 14 provides a second force F₂ to the second leg L₂, tendingto force the second leg L₂ into the extending position. The hamstringmuscle (antagonist muscle) of the second leg L₂ provides a secondresistance R₂ resisting the second force F₂, moving the second leg L₂into flexion. In this manner the quadriceps muscle of the first leg L₁and the hamstring muscle of the second leg L₂ are simultaneouslyexercised.

In the above described motion, the first and second bladders 12 and 14provide positive exertions to the quadricep muscle of the first leg L₁and the hamstring muscle of the second leg L₂. Upon completion of themotion, the first force F₁ is released, wherein, similar to freeweights, the bladder system 10 tends to conform back to the equilibriumposition, initial position. As such, the bladders 12 and 14 provideforces to the first and second legs as the fluid in the bladders 12 and14 moves to the equilibrium position. The resistance of these forcesprovides a negative exertion on the quadricep muscle of the first leg L₁and the hamstring muscle of the second leg L₂ as the first and secondlegs L₁ and L₂ move to the initial position.

Referring to FIG. 15B, the bladder system 10 of the present inventioncan be positioned in a leg machine such that as first leg L₁ is flexed,a first force F₁ is applied to the bladder 12. The bladder 12 provides afirst resistance R₁ to the hamstring muscle, agonist muscle, resistingthe flexion of the first leg L₁. Simultaneously and in response to thefirst force F₁, the fluid from bladder 12 is forced through the tube 16into bladder 14, expanding bladder 14. The expansion of bladder 14provides a second force F₂ to the second leg L₂, tending to force thesecond leg L₂ into the flexed position. The quadricep muscle, antagonistmuscle, of the second leg L₂ provides a second resistance R₂ resistingthe second force F₂, moving the second leg L₂ into an extended position.In this manner the hamstring muscle of the first leg L₁ and thequadricep muscle of the second leg L₂ are simultaneously exercised. Aswith the previous embodiment, the bladders 12 and 14 can likewiseprovide negative exertions on the hamstring muscle of the first leg L₁and the quadricep muscle of the second leg L₂ as the first and secondlegs L₁ and L₂ move to the initial position.

Referring to FIG. 16A, the bladder system 10 of the present inventioncan be positioned in a leg machine, such that the bladders 12 and 14provide forces to agonist and antagonist muscles of opposite legs,wherein the legs move in the same direction. The bladder 12 ispositioned in the leg machine such that when a first leg L₁ is extendedfrom an initial position a first force F₁ is applied to the bladder 12.The bladder 12 provides a first resistance R₁ to the quadricep muscleresisting the extension of the first leg L₁. Simultaneously and inresponse to the first force F₁, the fluid from bladder 12 is forcedthrough the tube 16 into bladder 14, expanding bladder 14. The expansionof bladder 14 provides a second force F₂ to the second leg L₂, forcingthe second leg L₂ into the extending position. The hamstring muscle ofthe second leg L₂ provides a second resistance R₂ resisting the secondforce F₂. In this manner the quadriceps muscle of the first leg L₁ isprovided with a positive exertion and the hamstring muscle of the secondleg L₂ is provided with a negative exertion.

Upon completion of the motion, both the first and second legs L₁ and L₂are in the extended position. Referring to FIG. 16B, the second leg L₂is then flexed, applying a third force F₃ to the bladder 14. The bladder14 provides a third resistance R₃ to the hamstring muscle resisting theflexion of the second leg L₂. Simultaneously and in response to thethird force F₃, the fluid from bladder 14 is forced through the tube 16into bladder 12, expanding bladder 12. The expansion of bladder 12provides a fourth force F₄ to the first leg L₁, forcing the first leg L₁into the flexed position. The quadricep muscle of the first leg L₁provides a fourth resistance R₄ resisting the fourth force F₄. The firstand second legs L₁ and L₂ are moved into the flexed position, initialposition. In this manner, the hamstring muscle of the second leg L₂ isprovided with a positive exertion and the quadricep muscle of the firstleg L₁ is provided with a negative exertion.

It is contemplated that the bladder 10, 102, or 108 can be used as astand alone device or incorporated into an exercise machinesystematically exercising agonist and antagonist muscle groups ofopposing limbs, such as, quadriceps/hamstring, biceps/triceps, etc. Itis further contemplated that regardless of the specific application, thedevice can include a tracking mechanism, such as a radio frequencyidentification (RFID) tag. One use for such a tracking mechanism wouldto be monitor patient compliance. In this regard, U.S. PatentPublication No. 2004/0215111, the contents of which are incorporated byreference herein, discloses a monitoring system and method that can beused with the present invention.

The bladder system of the present invention can be positioned on anexercise machine to provide a positive exertion to a first muscle and anegative exertion to a second muscle, wherein the first and secondmuscles include identical muscle on opposite limbs. Referring to FIG.17A, the bladder system 10 of the present invention is positioned on apreacher curl machine. The bladder 12 is positioned in the curl machinesuch that when a first arm A₁ is flexed from an initial position a firstforce F₁ is applied to the bladder 12. The bladder 12 provides a firstresistance R₁ to the bicep muscle, resisting the flexion of the firstarm A₁. Simultaneously and in response to the first force F₁, the fluidfrom bladder 12 is forced through the tube 16 into bladder 14, expandingbladder 14. The expansion of bladder 14 provides a second force F₂ tothe second arm A₂, forcing the second arm A₂ into the extendingposition. The bicep muscle of the second arm A₂ provides a secondresistance R₂ resisting the second force F₂. In this manner the bicepmuscle of the first arm A₁ is provided with an positive exertion and thebicep muscle of the second arm A₂ is provided with a negative exertion.

Referring to FIG. 17B, upon completion of the motion, the first arm A₁is in the flexed position and the second arm A₂ is in the extendedposition. The second arm A₂ is then flexed, applying the first force F₁to the bladder 14. The bladder 14 provides the first resistance R₁ tothe bicep muscle, resisting the flexion of the second arm L₁.Simultaneously and in response to the first force F1, the fluid frombladder 14 is forced through the tube 16 into bladder 12, expandingbladder 12. The expansion of bladder 12 provides the second force F₁ tothe first arm A₁, forcing the first arm A₁ into the extended position.The bicep muscle of the first arm A₁ provides the second resistance R₂resisting the second force F₂. The second arm A₂ is moved into theflexed position and the first arm A₁ is moved into the extendedposition. In this manner the bicep muscle of the second arm A₂ isprovided with a positive exertion and the bicep muscle of the first armA₁ is provided with a negative exertion.

It is contemplated that the bladder 10, 102, or 108 can be used as astand alone device or incorporated into an exercise machinesystematically exercising identical muscle groups of opposing limbs,such as, providing a positive exercise to the muscle of the first limband a negative exercise to the same muscle of the second limb. It isfurther contemplated that regardless of the specific application, thedevice can include a tracking mechanism, such as a radio frequencyidentification (RFID) tag. One use for such a tracking mechanism wouldto be monitor patient compliance. In this regard, the previouslyincorporated by reference U.S. Patent Publication No. 2004/0215111 canbe used with the present invention.

Referring to FIGS. 18 and 19, there is shown a cuff exercise system 120of the present invention. The cuff 120 includes an annular ring 122defining an annular bladder 124. The annular bladder 124 includes acompressible or non-compressible fluid 126 enclosed therein. The annularring 122 is made of an elastic material have a stiffness k_(R). Thestiffness k_(R) is selected to provide the desired resistance profile tothe muscle or muscle group being exercised.

In use, the annular ring 122 is positioned about a muscle or musclegroup. The contraction of the muscle pushes against the annular ring122, causing a compression of the fluid 126 and corresponding expansionof the annular ring 122. The stiffness k_(R) of the annular ring 122resists the expansion of the annular ring 122, imparting a compressiveforce about the muscles. As a result, the muscles 128 must provide anexpansive force to overcome the compressive force of the annular ring122.

Referring to FIG. 20, the annular ring 122 may be positioned about abicep muscle 128. When the arm 130 is flexed, the bicep muscle 128provides a pulling force to lift the weight 132, resulting in acontraction of the bicep muscle 128. The contracting bicep muscle 128expands, pushing against the annular ring 122, causing a compression ofthe fluid 126 and corresponding expansion of the annular ring 122. Thestiffness k_(R) of the annular ring 122 resists the expansion of theannular ring 122, imparting a compressive force about the bicep muscle128. As a result, the bicep muscle 128 must not only provide the pullingforce to lift the weight 132, but also an expansive force to overcomethe compressive force of the annular ring 122.

When lowering the weight, the bicep 128 provides a pulling force tocontrollable lower the weight 132. The compressive force applied by theannular ring 122 tends to increase the rate at which the weight 132 islowered. In order to maintain a controlled lowering rate, the bicep 128must provide an expansive force to overcome the compressive force of theannular ring 122.

The cuff 120 may include a mechanism for controlling the fluid pressurein the annular ring 122. The control mechanism may include a fill valvepositioned annular ring 122. Fluid 126 is added or removed from theannular ring 122, increasing or decreasing the fluid pressure therein.The fluid can progressively added to removed from the annular ring 122during the exercise to control the resistance profile.

Referring to FIG. 21, the cuff 120 can be positioned about any musclegroup, such as, abdominal/lower back, chest/upper back,quadriceps/hamstring, biceps/triceps, etc.

Referring to FIG. 22, the cuff 120 may be configured with attachmentsthat allow the cuff to be adjustably fitted about the muscle group. Forexample, the cuff 120 may have first and second end portions 134 and 136each including fastener members 138 and 140, to securely fit the cuff120 about the muscle. The fastener members 138 and 140 are adjustablemembers, allowing the cuff 120 to be securely, snugly, fitted about themuscle. For example, the fastener members 138 and 140 are hook-and-looptype fasteners, or could involve a plurality of snaps, zippers or otherfasteners.

Referring to FIG. 23, the cuff 120 includes a plurality of bladdermembers 144 positioned serially within the annular ring 122. Each of thebladder member 144 includes a compressible or non-compressible fluid 126enclosed therein and are made of elastic materials have a stiffnessk_(R). The stiffness k_(R) of each of the bladder members 144 isselected to provide the desired resistance profile to the muscle ormuscle group being exercised. Each of the bladder members 144 can havethe same stiffness k_(R) or a different stiffness k_(R), depending onthe desired resistance profile. Each of the adjacent bladder members 144can be fluidly connected with tube member 146. As described above, thetube members 146 may also be used to control the resistance profile.

Referring to FIG. 24, the cuff 120 includes a plurality of bladdermembers 148 positioned in a stacking arrangement within the annular ring122. Each of the bladder members 148 includes a compressible ornon-compressible fluid 126 enclosed therein and are made of elasticmaterials have a stiffness k_(R). The stiffnesses k_(R) of each of thebladder members 148 are selected to provide the desired resistanceprofile to the muscle or muscle group being exercised. Each of thebladder members 148 can have the same stiffness k_(R) or a differentstiffness k_(R), depending on the desired resistance profile. Each ofthe adjacent bladder members 148 can be fluidly connected with tubemember 150. As described above, the tube member 150 may also be used tocontrol the resistance profile.

In another embodiment, the bladder system of the present inventionincludes so-called “smart materials”. For example, the walls of thebladders may be constructed to include reinforcing fibers made of ashape memory alloy. A shape memory alloy possesses the properties ofreturning to an original shape after having been subjected to some formof deformation. The shape memory alloy returns to the original shapewith the application of an energy to heat the alloy to a temperatureabove a transformation temperature. In an exemplary use, the shapememory alloy is provided in the cuff exercise system 120 of FIGS. 18 and19.

As previously disclosed, the cuff exercise system 120 includes anannular ring 122 defining an annular bladder 124. The annular ring 122is positioned about a muscle or muscle group. The contraction of themuscle pushes against the annular ring 122, causing a compression of thefluid 126 and corresponding expansion of the annular ring 122. Thestiffness k_(R) of the annular ring 122 resists the expansion of theannular ring 122, imparting a compressive force about the muscles. As aresult, the muscles 128 must provide an expansive force to overcome thecompressive force of the annular ring 122.

The inclusion of the shape memory alloy in the annular bladder 124allows for a controlled application of the compressive force about themuscle. An application of an energy to the shape memory alloy,increasing the temperature of the shape memory alloy to the transitiontemperature, results in the shape memory alloy reverting to the originalshape. The original shape of the shape memory alloy is designed toincrease the stiffness k_(R) of the annular bladder 124, furtherincreasing the resistance to the expansion of the annular ring 122 andimparting an increased compressive force about the muscles.

It is contemplated that the annular bladder 124 can include a number ofdifferent shape memory alloys, each having a different transitiontemperature. The differing transition temperatures permit the shapememory alloys to be sequentially activated to increase the compressiveforce about the muscle.

The bladder system of the present invention can include anelectro-rheological (ER) fluid. An ER fluid is a fluid which changes itsphysical properties in the presence of an electric field. For example,the application of an electric field increases the viscosity of the ERfluid, which if desired, can ultimate change from a liquid to a solid.

Referring again to FIG. 1, the bladder system 10 of the presentinvention uses a plurality of fluidly connected bladders to provideresistive forces to the muscles being exercised. The bladder system 10includes first and second bladders 12 and 14 in fluid communication witheach other, such as through a tube 16.

An ER fluid 18 is disposed within the bladders 12 and 14, such that acompression of one of the bladders 12 or 14 forces the ER fluid 18through the tube 16 into the opposite bladder 12 or 14. The viscosity ofthe ER fluid 18 is used to control the resistance of the exercisedevice. The viscosity of the ER fluid 18 is selected to provide aspecific maximum flow rate through the tube 16 without the presence ofthe electric field. The application of the electric field increases theviscosity of the ER fluid 18, decreasing the flow rate and providing agreater resistance. As the intensity of the electric field is increased,the viscosity of the ER fluid is similarly increased, increasing theresistance.

The smart materials of the above embodiments may be used individually orin combination to provide a bladder system having an increased range ofuseful resistance. Additionally, while having been described on specificembodiment of the present invention, this is for exemplary purposes onlyand it is contemplated that the smart materials can be similarlyincorporated into other embodiments of the present invention.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed herein above. In addition, unless mention was made above tothe contrary, it should be noted that all of the accompanying drawingsare not to scale. A variety of modifications and variations are possiblein light of the above teachings without departing from the scope andspirit of the invention, which is limited only by the following claims.

What is claimed is:
 1. An exercise device comprising: a first memberconfigured to apply a first resistance force to a first tissue duringflexion of the first tissue to enhance a flexion force applied by thefirst tissue; and a second member configured to apply a secondresistance force to a second tissue during flexion of the first tissue,wherein the first and second resistance forces are configured tosystematically exercise the first and second tissues.
 2. The device ofclaim 1, wherein the first and second tissues include agonist muscles.3. The device of claim 2, wherein the muscles include a chest and anupper back
 4. The device of claim 2, wherein the muscles include anabdominal and a lower back.
 5. The device of claim 2, wherein themuscles include a quadricep and a hamstring.
 6. The device of claim 2,wherein the muscles include a bicep and a tricep.
 7. The device of claim1, wherein the first or second member is responsive to an electricfield.
 8. The device of claim 7, wherein the first or second resistanceforce increases with an increase in the intensity of the electric field.9. The device of claim 1, further comprising a transducer to measure thefirst or second resistance force.
 10. The device of claim 1, wherein thefirst or second member includes a gel.
 11. An exercise devicecomprising: a first member configured to apply a first resistance forceat or over a first tissue during flexion of the first tissue to enhancea flexion force applied by the first tissue; and a second memberconfigured to apply a second resistance force at or over a second tissueduring flexion of the first tissue, wherein the first and secondresistance forces are configured to systematically exercise the firstand second tissues.
 12. The device of claim 11, wherein the first andsecond tissues include agonist muscles.
 13. The device of claim 11,wherein the first or second tissue includes a muscle of a chest, upperback, abdominal, lower back, quadricep, hamstring, bicep, or tricep. 14.The device of claim 11, wherein the first or second member is configuredto respond to an electric field.
 15. The device of claim 14, wherein thefirst or second resistance force increases with an increase in theintensity of the electric field.
 16. The device of claim 11, furthercomprising a transducer to measure the first or second resistance force.17. The device of claim 11, wherein the first or second member includesa gel.
 18. An exercise device comprising: a first member configured toapply a resistance force to a tissue during flexion of the tissue toenhance a flexion force by the tissue; and a second member configured torespond to an electrical field to increase the resistance force appliedto the tissue, wherein the first and second members are configured toenhance exercise of the tissue.
 19. The device of claim 18, wherein thetissue includes a muscle of a chest, upper back, abdominal, lower back,quadricep, hamstring, bicep, or tricep.
 20. The device of claim 18,further comprising a transducer to measure the resistance force.
 21. Thedevice of claim 18, wherein the first or second member includes a gel.